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PERTEMUAN 3 Basic Digital Logic Combinational Logic Created for the D3 and S1 Terapan PNJ Zulhelman [email protected] September2013 1 Basic Digital Logic 2 Review 2 Review ◊ Digital Electronics makes use of 2 states: ◊ Logic High, or “1” ◊ Logic Low, or “0” 3 Review ◊ There are 3 basic digital gates: ◊ AND ◊ OR ◊ NOT 4 Review AND, where ALL inputs must be “1” for the output to be “1” OR, where ANY of the inputs can be “1” for the output to be “1” NOT (or the Inverter) where the output is the opposite (compliment) of the input. 5 Review Questions What is the outcome of the following: 1 1 1 1 0 1 0 6 Truth Tables and Boolean Notation ◊ Circuits with one input ◊ Buffer ◊ Not P=A P=A A P 0 0 1 1 A P 0 1 1 0 A P A P Basic AND / OR ◊ Circuits with two Inputs ◊ AND P = A.B A 0 0 1 1 B 0 1 0 1 P 0 0 0 1 ◊ OR A 0 0 1 1 B 0 1 0 1 P 0 1 1 1 P=A+B A B P A B P Basic NAND / NOR ◊ Problems with two Inputs ◊ NAND ◊ NOR P= A 0 A.B 0 1 1 B 0 1 0 1 P 1 1 1 0 A B A 0 0 1 1 B 0 1 0 1 P 1 0 0 0 A B P=A+B P P Basic XOR / XNOR ◊ Circuits with two Inputs: ◊ XOR P = A B ◊ XNOR P=AB A 0 0 1 1 A 0 0 1 1 B 0 1 0 1 B 0 1 0 1 P 0 1 1 0 P 1 0 0 1 A B A B P P Primitive gates ◊ All circuits can actually be made using AND, OR and NOT gates if required. Exercise Complete the truth table for this circuit and name the equivalent primitive function/gate. A B A+B A.B A.B P 0 0 0 0 1 0 0 1 1 0 1 1 1 0 1 0 1 1 1 1 1 1 0 0 Basic Digital Logic 2 Basic Combinational Logic, NAND and NOR gates 13 Combinational Logic ◊ A circuit that utilizes more that 1 logic function has Combinational Logic. ◊ As an example, if a circuit has an AND gate connected to an Inverter gate, this circuit has combinational logic. 14 Combinational logic ◊ How would your describe the output of this combinational logic circuit? 15 NAND Gate ◊ The NAND gate is the combination of an NOT gate with an AND gate. The Bubble in front of the gate is an inverter. 16 Combinational logic ◊ How would your describe the output of this combinational logic circuit? 17 NOR gate ◊ The NOR gate is the combination of the NOT gate with the OR gate. The Bubble in front of the gate is an inverter. 18 NAND and NOR gates ◊ The NAND and NOR gates are very popular as they can be connected in more ways that the simple AND and OR gates. 19 Exercise 1 Complete the Truth Table for the NAND and NOR Gates NOR NAND Input Output Input 0 0 0 0 0 1 0 1 1 0 1 0 1 1 1 1 Output Hint: Think of the AND and OR truth tables. The outputs for the NAND and NOR are inverted. 20 Basic XOR / XNOR ◊ Circuits with two Inputs: ◊ XOR P = A B ◊ XNOR P=AB A 0 0 1 1 B 0 1 0 1 A 0 0 1 1 P 0 1 1 0 B 0 1 0 1 A B P 1 0 0 1 A B P P Basic Digital Logic 2 Chips and Gates 22 Basic Digital Chips ◊ Digital Electronics devices are usually in a chip format. ◊ The chip is identified with a part number or a model number. ◊ A standard series starts with numbers 74, 4, or 14. ◊ ◊ ◊ ◊ 7404 is an inverter 7408 is an AND 7432 is an OR 4011B is a NAND 23 Chips ◊ Basic logic chips often come in 14-pin packages. ◊ Package sizes and styles vary. ◊ Pin 1 is indicated with a dot or halfcircle ◊ Numbers are read counter-clockwise from pin 1 (viewed from the top) Pin 14 Pin 8 Pin 1 Pin 7 24 Chips ◊ Chips require a voltage to function Pin 14 Pin 8 Pin 1 Pin 7 ◊ Vcc is equal to 5 volts and is typically pin 14 ◊ Ground is typically pin 7 25 Chips – Specification Sheet Voltage The voltage and ground pins must be connected for the device to function. Check the specification sheet to make sure. Ground Diagram from http://www.onsemi.com 26 Chips – Specification Sheet A B C D Diagrams from http://www.onsemi.com 27 Wiring a chip IN IN Vcc OUT Vcc Probe 28 Example ◊ Consider a buzzer which sounds when : ◊ The lights are on and A Alarm B system ◊ The door is open and C ◊ No key is in the ignition Variable Value Situation A 1 Lights are on 0 Lights are off B 1 Door is open 0 Door is closed C 1 Key is in ignition 0 Key is out of ignition P 1 Buzzer is on 0 Buzzer is off P Active Example ◊ Truth Table ◊ A Truth Table can be used to show the relationships between : ◊ the 3 inputs and ◊ the single output A B C P 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 0 1 1 0 1 1 1 1 0 lights A door B ◊ Implementation as a circuit using logic gates keys C P buzzer Useful Resources ◊ ◊ ◊ ◊ Textbooks on Digital Electronics (used is ok!) Electronics Workbench or other electronic simulation software Craig Maynard’s Virtual Vulcan The following web sites: ◊ ◊ ◊ http://learnat.sait.ab.ca/ict/digi240_godin/default.htm http://learnat.sait.ab.ca/ict/cmph200/Default.htm http://learnat.sait.ab.ca/ict/cmph200_godin/default.htm ◊ ◊ ◊ http://focus.ti.com/docs/logic/logichomepage.jhtml http://www.onsemi.com http://www.national.com/ ◊ ◊ ◊ http://www.play-hookey.com/digital/ http://www.crhc.uiuc.edu/~drburke/databookshelf.html http://www.digikey.ca/ 31 Lab Exercise ◊ Using the experimenter’s boards, connect the circuit provided to you in the following pages. 32 Layout of the SK-10 Experimenter's Board 33 Layout of the SK-10 Experimenter's Board Flat Side 7400 Wires 34 Logic Diagram of Lab 35 End of Basic Digital Logic 2 Copyright WCRS and Paul Godin For non-profit use only 36